Macro that generate struct

help
1

How to generate a struct with macro? let's say we have a JSON which is like:

{
    "fields": [{
          "name": "a",
          "type": "String"
    }]
}

and generate a struct like:

struct Foo {
    a: String
}
2

Ignoring the fact that the struct name isn't specified anywhere, you would need a proc macro due to the fact that the field name and type are strings.

3

Would you mind being more explicit? and how to pass the content of a vec to the macro since fields is actually JSON array

4

Right now "Foo" isn't specified anywhere in the JSON, so you have to figure out how you're coming up with the struct name.

You will have to use a procedural macro, which takes the raw tokens from the compiler. It's not going to be trivial to do. If all you want is a JSON-like syntax and not actual JSON, you should not add quotes around the field name and type, which will let you use macro_rules!.

5

You can probably use a build script here.
A build script is a rust program that runs before the rest of the code is compiled.
It would read the json file and write the strut to be generated into a file that is then included in the remaining Rust code.

https://doc.rust-lang.org/cargo/reference/build-scripts.html

6

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